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green rotal rotundifolia

I'm still confused by this I'm unfortunately one of those thick people with what's now called learning difficulties.
Are you saying that lower intensity actually improves growth? I noticed that when I used 2 green peaking bulbs in my luminaire growth was poor but when I used one yellow and one green peaking growth was much much improved. Am I seeing something that isn't there or is it actually spectral?
 
Thank you Ceg, great explanation, I had not considered the colours of light mixing

Garuf- I don't think anyone is saying lower light will improve growth, just that we cannot tell what colour light a plant needs by the colour of it's leaves.

Cheers
James
 
Hhmm, yes i see that but if growth was poor with the t5's but good with the lower intensity t8's surely there's something more than just spectral change at play?
 
TBH I'm not sure what's going on. With the T5's I ran just on two tubes for a while and it made no difference to when I used all four tubes. I'm still a firm believer that plants mainly use red and blue light for photosynthesis which is why you get poor results when using cheapo 6500 tubes as they have little red or blue light. Replace the cheapo 6500 tube with a decent wide spectrum 6500 tube and see what a difference it makes.

I had two 54W (108W) T5 tubes approx 9-10 inches from the water's surface which produced green rotundifolia and now have four 38W (152W) T8 tubes approx 1.5 inches from the surface producing red rotundifolia. Yes the T5's are more intense but they were much further away from the water's surface and also a third less in wattage than the T8's.

With the spectrum the main thing that has changed is that I now have less green light and more blue purple light. I have read articles some time ago that UV light can make some plants go redder. Possibly the blue/purple GE 10K tubes also have this effect. It's only speculation though so don't please go saying it's a fact in other posts.

Anyway what ever has caused the change happened very dramatically after only a day or two. Also of note is that I have also noticed last night that the blyxa japonica I have is turning a coppery red colour.

Food for thought
James
 
Garuf said:
Are you saying that lower intensity actually improves growth?
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I brought into the 'more light is better' idea a while ago which is why I went out and purchased a Arcadia luminaire with 4 T5's. But ever since I've never been as happy as I was before with the T8's. Having spent the money I just didn't want accept that it was a waste and I should've stuck with the T8's. My main objective to higher lighting was to produce stronger red's in my plants, but as it turned out it produced less red's :lol: .

There are many reasons though for improved growth having lower light with probably the main ones being nutrient and CO2 availability.

James
 
JamesC said:
TBH I'm not sure what's going on. With the T5's I ran just on two tubes for a while and it made no difference to when I used all four tubes. I'm still a firm believer that plants mainly use red and blue light for photosynthesis which is why you get poor results when using cheapo 6500 tubes as they have little red or blue light. Replace the cheapo 6500 tube with a decent wide spectrum 6500 tube and see what a difference it makes.

I had two 54W (108W) T5 tubes approx 9-10 inches from the water's surface which produced green rotundifolia and now have four 38W (152W) T8 tubes approx 1.5 inches from the surface producing red rotundifolia. Yes the T5's are more intense but they were much further away from the water's surface and also a third less in wattage than the T8's.

With the spectrum the main thing that has changed is that I now have less green light and more blue purple light. I have read articles some time ago that UV light can make some plants go redder. Possibly the blue/purple GE 10K tubes also have this effect. It's only speculation though so don't please go saying it's a fact in other posts.

Anyway what ever has caused the change happened very dramatically after only a day or two. Also of note is that I have also noticed last night that the blyxa japonica I have is turning a coppery red colour.

Food for thought
James
Click to expand...


and is the light duration the same?
i cut my t5's down by one hour last week and the pink/red has pretty much totally gone from my rotundifolia!
 
Yep, there are a lot of factors that combine and that's what makes it befuddling. I've mostly used cheapo bulbs, often those having high green content and I've never had difficulty with pearling or growth performance when compared to the so-called high quality bulbs.

The variability in delivery between bulb types combined with the variation in distances makes it really tough to judge how much difference is actually delivered to the leaf surface.

One thing to consider is that by default, blue and violet wavelengths delivers higher PAR simply as a result of their comparatively higher frequencies. The difference in photon delivery from green to blue is on the order of a 10-15% increase while that from green to violet is on the order of 25-50% increase, so even staying within the same general output wattage rating there is an immediate increase in photon delivery if that bulb has a higher blue/violet content.

While it's undeniable that blue and red wavelengths are the primary photosynthetic wavelengths it is far from a certainty that green wavelengths are useless. I'm fairly certain that this is another myth perpetuated in The Matrix but it's difficult to find conclusive data. The closest definitive report that's available for free is a 2009 joint study by The Biological Department at The University of Tokyo and The School of Biology at The Australian National University, Canberra in which they concluded that the photosynthetic quantum yield of green light was actually superior to that of red light. They determined that it was specifically because of the lower absorption of green that allowed these wavelengths to penetrate to the lower palisade region of the chloroplast bundles in order to maximize light availability to the lower portions of the bundles. Internal reflectance of the leaf tissues actually allows better utilization of green light. An extremely advanced journal, but well worth the effort: Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light: Revisiting the Enigmatic Question of Why Leaves are Green Check the graphs at the very end (Figure 10). Amazing stuff. :geek:

More data showing a reversal of the trend in green wavelength bashing are presented in the somewhat tedious Green light: a signal to slow down or stop which discusses some of the physiological reactions of green wavelengths.

There are also direct data showing effects on chloroplast production and size in the article Effects of Green Light on the Chloroplasts of Spinach Leaf Discs

Cheers,
 
I used to get seriously red Rotala in my Juwel Lido, but always thought that it was because it was Greenline Rotala as opposed to Tropica, which I have never turned red under my Arcadia T8 lamps, which are their freshwater tubes.

The Lido is in storage at the moment, but when I get the chance, I`ll have a look at the tubes. I think they were Interpet compact T5s, one being a Triplus, and the other being a Daylight.

I have never seen any red Rotala (Tropica) under Geisemann T5s either.

Dave.
 
Without having read the entire thread, I will offer my (limited) experience with rotundifolia.

Mine only turns red when it is within approx. 1.5 inches of the water's surface, total depth of water approx. 15inches allowing for substrate, they continue to turn a brighter red if left to grown along the surface.

After trimming and replanting the tops the leaves turn a dirty red-brown and sometimes die off.

My lighting is Activa 172
 
I never said plants don't use green light. This is what I said
plants mainly use red and blue light for photosynthesis
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Yes plants can use green light but mostly they use the red and blue parts of the spectrum, except it seems that under very strong white light, green light may be used more efficiently. Even cheapo daylight tubes normally have red and blue light so will grow plants fine. I would think that in our relatively dim tanks that red's and blues are the main parts of the spectrum used and is what I've noticed. Anyway this is going off topic.

An experiment was done with red cabbages where one lot was grown under a UV filter and the other lot was not. The cabbages under the UV filter stayed green whilst the other lot turned red. This may have nothing to do with my rotundifolia but got me thinking. Perhaps some tubes do emit small amounts of UV. My Arcadia luminaire with the T5's uses a protective cover to prevent water splashing, which might also filter out certain wavelenghs. The T8's I use rest directly on the tank's braces so have nothing that could filter the light. It's all speculation though but something has made a dramatic change in the plants.

Oh, and I've tried both the Tropica and Aqua Fleur R.Rotundifolia which seem to be exactly the same.

James
 
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